1. Field of the Invention
The present invention relates to encoding and decoding of moving pictures. More particularly, the present invention relates to a method of and apparatus for efficiently performing encoding and decoding by reconstructing patches of an icosahedron panorama moving picture.
2. Description of the Related Art
An omni-directional video camera system is a camera system that is capable of taking 360-degree omni-directional images from a fixed viewpoint. The omni-directional video camera system takes omni-directional images by mounting and using a special shape mirror such as a hyperboloid mirror, a special lens such as a fish eye lens, or by using a plurality of cameras.
A 3-dimensional realistic broadcasting system is presented as an example of an omni-directional video coding applications for use with such a system. In the 3-dimensional realistic broadcasting system, all image information on views from various viewpoints in a baseball game and the like, for example, is provided to viewer terminals. That is, a variety of image information items, including the view from the pitcher, the view from the catcher, the view from the batter, the view from the audience sitting near first base, are provided to the viewers. Viewers can select a desired viewpoint and view the image from that viewpoint.
An image photographed by the omni-directional camera system has a characteristic corresponding to a 3-dimensional spherical environment. Accordingly, a 3-dimensional image taken by the omni-directional camera system is converted into a 2-dimensional plane image. At this time, the 2-dimensional plane image becomes a panorama image containing the omni-directional image. Omni-directional video coding is performed for the 2-dimensional panorama image.
Generally, the panorama image has a size much larger than that of a conventional 2-dimensional image, and in order to transmit a quality image, requires an excessively large bandwidth. Accordingly, it is very important to efficiently code the image.
Research on a variety of methods for processing the omni-directional image is currently being conducted. In particular, when an icosahedron image is applied to video coding, the developed or resulting figure is formed using 20 equilateral-triangle-shaped patch images, as shown in FIG. 1, and matches relatively accurately with a sphere. Accordingly, the panorama image processing has become a popular research area.
FIG. 2 illustrates a conventional method of coding an icosahedron panorama image. First, a boundary line such as a rectangle marked with dotted lines for an icosahedron is set, and macroblocks are arranged to include all of the boundary line. Then, the icosahedron panorama image is coded in units of blocks.
Black colored blocks are blocks outside the icosahedron having no image information. When encoding and decoding are performed, a skip operation is performed for the black colored blocks.
White colored blocks are blocks inside the icosahedron that are coded using a conventional frame unit coding method. However, gray colored blocks are located on the boundaries of respective patches, and if the conventional frame unit coding technique is used, a lot of high frequency components occur on the boundary such that the coding efficiency is quickly degraded.
For example, in order to process the icosahedron panorama image of FIG. 2, a total of 288 macroblocks comprising 24 blocks in width and 12 blocks in length should be processed, and among them, 109 macroblocks on the boundary part should be processed, which means that low efficiency coding is performed in 38% of the macroblocks. For example, in order to process patches 1, 5, 9, 13, and 17 of the top part, 47 macroblocks out of a total of 96 macroblocks are on the boundary part, which means that low efficiency coding is performed in about 49% of the macroblock on the top part.
Therefore, a need exists for an apparatus and method of efficiently processing an icosahedron panorama image. Specifically, a need exists for efficiently processing the macroblocks of an icosahedron panorama image.